How to code a Game Grid in Java?

Question

Suppose I wanted to code a game grid in java. Not an abstract text one but an actual grid with graphics and 'cells'. Would I have to draw line by line or is there a more efficient way? Also how would I go moving units (objects) around the grid, moving them and repainting their positions?

  public static int [] [] map = {{2,0,1,0,0}, // e.g. 2 is base
                                   {1,0,0,0,0},
                                   {0,0,0,0,0},  //1 is unit
                                   {0,0,0,0,0},
                                   {0,0,0,0,2}};

I still wonder if there is a resemblance between 2D arrays and actual game grids as I can just paint coordinates and lines. However I feel there is a better way and want to implement a structure like above (the code) to emulate a map like this:

Answer 1

You should read about tiled maps, tiles and tilesets.

Your tiled map is a grid. It's simply a 2D array where each element of the array is a tile. Using a 2D array in this case seems perfect since you can easily access a tile at a given position by doing mapArray[x][y].

Now you need to define a way to represent the tiles of your map. Here come the concept of tileset. A tileset is basically an image containing a collection of tiles, here is an example of a random tileset I picked on the internet:

Since you know that the tiles of your map will always have the same dimensions (16x16, 32x32 etc.), you can easily extract the tiles from the tileset and assign an id to each of them. The first tile in the tileset could have the id 0, the second one, the id 1 and so on. Then, why not do something like tileset[id] to get actual tile's image?

This way, your map could be a 2D array of integers representing tile's id. When creating your map, you will need to link your map array with the tileset(s) used to render it.

If you decide to use frameworks such as Slick2D or LibGDX, they often have build in facilities to manipulate tiled maps.

Plus, some tiled map editors exists:

• Tiled
• tIDE

Answer 2

A way you could do it is an array of images which would most likely require a library. I'm a C++ coder but say the library has an object called an Image. You could make an array of this a new Image object and set specific values of that array to different images. Like...

Image map[] = {{"something.png"},{"another.png"}} ...

And then maybe you could make another normal int array to actually set-up the map layout while using values of the int array to apply to the values of the Image array but you couldn't set them equal to each other since they're different types.